1. Field of the Invention
The present invention pertains to a friction clutch for use in the drive train of a motor vehicle with an input part, a clutch housing, at least one clutch disk in working connection with a takeoff element, and a pressure plate working together with the input part, the force of a stored-energy device acting on the pressure plate to transmit torque to the clutch disk.
2. Description of the Related Art
U.S. Pat. No. 5,779,018 discloses a multi-disk friction clutch in which the several clutch disks are designed in the form of a set of plates connected to a common hub part. In the clutch housing, a pressure plate is provided, which can be acted upon by a stored-energy device, and in addition several intermediate disks are connected nonrotatably to the clutch housing, these intermediate disks engaging between the plates. By means of the stored-energy device, the intermediate disks and the plates can be pressed against each other to generate mutual frictional contact. The stored-energy device, which here has the form of a diaphragm spring, is situated inside the housing and is essentially parallel the bottom of the housing so that one side of it can be supported against the housing, while the other side is in contact with the pressure plate and can thus exert the required force.
In a friction clutch of this type, there is the problem that the supply of cooling air to the interior of the clutch is limited. This means that the clutch can overheat at least when it is slipping for an extended period of time.
This known friction clutch also suffers from the problem that the housing is manufactured by means of complicated, multi-stage processes.
It is the task of the present invention to provide a friction clutch in which the flow of cooling air to the components which become heated during operation is improved, and the individual parts of which can also be produced at low cost.
According to the invention, the radially outer area of the input part has walls extending in the axial direction to cooperate with the pressure plate, these walls extending around at least a portion of the circumference.
It is also proposed that the walls for the friction clutch according to the invention be designed with graduations in the circumferential direction.
As a result of this measure, it becomes less expensive to fabricate the friction clutch, especially when castings are used, and fewer work steps are required to assemble it.
It can be provided, for example, that the axially oriented walls have attachment sections, which can be used to fasten the walls to the housing. The housing can also be connected to the wall by fastening means such as screws or bolts. As a result, it becomes very easy to assemble the friction clutch. The friction clutch, especially the input part with the housing, also becomes stiffened when the housing is supported primarily on the axially oriented walls, and the two components are centered with respect to each other in a relatively low-cost manner. The mass moment of inertia is also considerably reduced when at least a certain area of the axially oriented part of the wall has sections of different axial length.
In a concrete embodiment of the invention, it is preferable for each wall to have an attachment section near the base of the input part to cooperate with a fastening means. In addition, an area where the fastening means is subjected to an elastic load is provided next to the attachment section in the axial direction. This makes it possible, first, to increase the stiffness of the input part with respect to the shrouding and, second, to minimize the effects of centrifugal force on the axial wall. This is because the attachment section reduces the bending stresses which occur in the base area of the axial wall as a result of centrifugal force; at the same time, if a certain part of the fastening means is free to be elastically deformed, the fastening means can be preloaded in a controlled manner. To keep down costs and to minimize the amount of work required to manufacture the input part, it is also proposed that the area where the fastening means is deformed be provided in the wall. While elastic load is being exerted on the fastening means, furthermore, the housing will also be elastically deformed in the attachment area. By designing the area of the housing near the fastening means and the area of the housing where it makes contact with the input part in such a way that the housing is elastically deformed at least in the axial direction, it is possible to increase even more the reliability of the assembly process and to reduce the error rate with respect to defective connections. For this purpose, either the housing can have a bulge pointing away from the fastening direction in the contact area with the fastening means, or alternatively the input part can have a depression in this area. The housing is preferably supported in this case against the end surface of the part of the wall extending in the axial direction; there can be one of these end surfaces at each circumferential end of each attachment area.
To obtain the rotating coupling between the input part and the pressure plate, several separate guide surfaces facing in the circumferential direction are provided on the axial walls of the input part, and the axially oriented walls extend around at least part of the circumference of the input part. The guide surfaces are thus able to enter into a working connection with the pressure plate. As a result of this design, the axially oriented walls are made stronger, and the number of different parts required to assemble the friction clutch is reduced to a minimum.
The pressure plate has radial projections to engage with the walls, as a result of which the torque can be transmitted from the input part to the pressure plate; in addition, the pressure plate is free to move axially with respect to the input part.
So that the greatest possible amount of power and high torque can be transmitted via the friction clutch, it is proposed that an additional clutch disk and an intermediate disk be provided, the intermediate disk being provided with radial projections to engage with the axial walls of the input part.
The friction clutch will operate especially advantageously during the engagement and disengagement processes if the pressure plate or the intermediate disk has first radial projections primarily for transmitting torque in the engaged state and second radial projections for guiding the pressure plate or intermediate disk during the engagement process. Both the pressure plate and the intermediate disk can have these projections, in which case the corresponding first and second projections on the pressure plate are preferably designed to be congruent with those on the intermediate disk.
To reduce the stresses resulting from centrifugal forces, the housing can have an outer area which works together with centering sections of the walls. This is also an especially simple way of centering the housing and the input part with respect to each other and their common axis of rotation.
The structure of the input part can be adapted to the transmission of high torques by providing several sections arranged in succession around the circumference of the input part, each one comprising a wall extending in the axial direction, and by removing material from the sections between the sides facing in the circumferential direction to reduce the centrifugal forces. The input part can be manufactured very cheaply especially when the area of removed material is present at least at the end of the axial wall facing the housing. This makes it easy to machine the casting to its final shape after solidification.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.